UBIFS: improve lprops dump

Improve 'dbg_dump_lprop()' and print dark and dead space there,
decode flags, and journal heads.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

diff --cc fs/ubifs/debug.c
Simple merge

diff --cc fs/ubifs/lprops.c
Simple merge

diff --cc fs/ubifs/ubifs.h
Simple merge